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Old 02-23-2011, 09:22 AM
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Originally Posted by jeepers creepers
I've read lot of things on the forum about the causes of oil pressure drop, oil level, windage tray, oil pick up height and its related brazing to the pumo body can afflict pressure.
Mine is very good, about 70 when cold and over 35 at idle at operating temperature, the problem pop out when engine turns close to 5000 rpm, the gauge pointer has a superfast vibration from around 5 to 35 PSI.
Looking for the cause on the web i've seen that some oil pump has problem over 5000rpm or so, any experience with them?

i'll tear down oil pan to check pick up height first (honestly i want to see bearings too) then braze the pick up or make a bracket for it.
This is a mechanical gauge? Because if it's electrical, look for a bad connection.

The first thing I always look on ANY gauge when I get an abnormal, 'screwy' reading is the sender and the gauge. Check the pressure using another gauge, and check the connections, especially if you're using plastic tubing.

Cavitation IS what comes to mind, though. This is most often caused by the pickup being too close to the bottom of the pan rather than the PU being too high. And as you've suspected, the pump can pull air past a pressed on tube, although this isn't common especially if a new PU was pressed on correctly. But if the old PU was reused, or the job wasn't done just so, you can still pull air.

Use a good oil filter, too. The Fram filters have been reported to have problems associated w/pressure loss.

Not at all likely to be the problem, but still worth mentioning is the filter mount bypass. I like to block it off so the filter receives all the oil, but caution must be used when the oil is cold, and to keep an eye on the pressure- it will continue to drop as the filter becomes more and more restricted.

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